Membrane-filter bubble-point test

摘要

In a recent article on caspofungin acetate compatibility, the bubble-point test of filter membranes—used to collect precipitates—was described as resistance felt on a syringe plunger in response to hand-applied air pressure.1 The correct bubble-point test employs a gauge to verify that bubbles do not form below a manufacturer-specified pressure value when the downstream orifice of an airtight apparatus holding a wetted filter membrane is immersed in water, and air or nitrogen flow is applied upstream.2–7 Gas bubbles at the specified pressure represent intactness of the nominal pore or capillary size of the filter membrane. Bubbles generated at a pressure lower than the specified one indicate a detached, ruptured, or punctured membrane.